Abstract:
We present a simple and very convincing approach to visualizing that subsequent layers of
graphene grow between the existing monolayer graphene and the copper catalyst in chemical
vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto
glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly
(methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield
graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic
force microscopy (AFM) were used to reveal surface features for both the DT and IT
samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed
the underlayer growth of subsequent layers. The subsequent layers in the IT samples are
visualized as 3D structures, where the smaller graphene layers lie above the larger layers
stacked in a concentric manner. The results support the formation of the so-called “inverted
wedding cake” stacking in multilayer graphene growth.
